The present invention concerns a control valve arrangement for a hydraulic shock absorber which may be used, for example, in a motor vehicle suspension system. More particularly, the invention relates to a fluid control valve for a shock absorber of the type disclosed in the German Pat. No. 833,574.
The German Pat. No. 833,574 discloses a shock absorber having a bottom valve arrangement with separate ducts for the two directions of flow between the cylinder and the surrounding fluid tank. This construction offers the advantage that any foam possibly forming in the region of the ducts can rapidly be swept away. In addition, the series arrangement of a working valve and an auxiliary check valve in the duct which passes fluid in the operating direction during piston retraction makes it possible to reduce the hysteresis of the shock absorber to a very low valve. Moreover, the auxiliary valve delays the withdrawal of fluid from the working chamber within the cylinder.
The construction of the bottom valve arrangement with a suction valve in one duct and a working valve and an auxiliary valve in the other, as described in the aforementioned patent specification, requires a complex partition element which must form all three valve seats and must secure the plate spring discs forming the two valves that are effective in the operating direction. In order to mount the various valve bodies in the partition, two flanging processes are required which necessitate relatively complicated supporting elements because of the positions of the supporting surfaces or supporting edges. If one of the flanges is removed, for example to facilitate repair, this complexly constructed partition element has to be discarded and replaced.
As mentioned above, the plate springs in this known type of shock absorber which constitute the two valve bodies are clamped over a given radially-extending area so that they are subjected to considerable bending stress during operation and may prematurely fail.
All of these shortcomings render the known construction of the shock absorber control valve unfit for practical use. Therefore, it is an object of the invention to provide a control valve arrangement for a shock absorber of the type described above which has the same fundamental advantages but which is substantially simpler with respect to construction and assembly and is less susceptable to failure.